Marijuana use is the most frequently used illicit substance among emerging adults (those between the ages of 18 and 25) and is associated with elevated risk for a number of undesirable consequences. While empirically supported indicated prevention interventions targeting at-risk alcohol use are widely available for this population, especially in college settings, similar interventions for marijuana are not currently available. The purpose of the present application is to build on our previous studies utilizing personalized feedback for marijuana through enhancing marijuana-specific content of the intervention and utilizing feedback within the context of an in-person motivational intervention. The overall objectives of this program of research are to reduce prevalence and frequency of marijuana use and related consequences among emerging adults during the transition to adulthood, through the development of efficacious indicated prevention techniques for at-risk users. In the current application, we will develop and evaluate an in-person brief motivational personalized feedback intervention for frequent marijuana using college students. The intervention will focus on unique and specific characteristics for marijuana use from developmental and social perspectives, including specific motivations and contexts for use, perceptions of risk in relation to important social, cognitive, and motivational goals, and normative social influences and the influence of social identity. Frequent marijuana users from two public colleges will be recruited to particpate in a longitudinal efficacy trial. Students will complete online screening and baseline assessments and will be randomly assigned to either an in-person motivational intervention or an assessment-only control condition following completion of a baseline assessment. Follow-up assessments will occur post-intervention, and at 3- and 6-months. In addition to evaluating intervention efficacy, we will evaluate mediators (e.g., marijuana motives, perceived risk, normative perceptions, and attitudes regarding personal goals and marijuana use) and moderators (e.g., readiness to change, social identity) of intervention efficacy. The proposed research is a natural extension of our previous and ongoing work and has the potential to offer a needed option for emerging adult marijuana users who may be on a trajectory toward potentially life-altering negative consequences related to their marijuana use. PUBLIC HEALTH RELEVANCE: Frequent marijuana use has a number of consequences related to public health. College administrators who may wish to provide services for addressing frequent marijuana use on their campuses currently have a dearth of empirically supported options to choose from. The proposed research will develop and evaluate a motivational intervention for frequent marijuana use among college students, which if succesful could have important heath benefits for the individual but could also be widely disseminated across college campuses.